How to isolate the strong and weak current wiring in an electrical power measurement switch (PMS)?

If the high-voltage (main circuit, drive power supply) and low-voltage (measurement, control signal) lines within a PMS are improperly routed, the strong magnetic field generated by the high-voltage circuit and the electric field through parasitic capacitance will severely couple and interfere with the low-voltage circuit. The core principle of isolated routing is "spatial separation, vertical crossing, and shielded isolation." Spatially, in PCB and wire harness layout, high-voltage and low-voltage paths should be placed in different areas or cable trays, maintaining minimum spacing: for 400VAC/100A high-voltage circuits, the parallel spacing with low-voltage signal lines should be greater than 20mm. When proximity is unavoidable, perpendicular crossings should be used instead of parallel routing.

For long-distance parallel routing, a grounded metal shielding partition must be installed in the middle. On the PCB, a minimum 3mm isolation slot should be opened between high-voltage and low-voltage areas, and a Y capacitor (such as 2.2nF/Y1) or a common-mode inductor CMZ2012A-900T should be connected across the slot to provide a safe high-frequency connection. Low-voltage signal lines should preferably use twisted-pair or shielded cables, with the shielding layer grounded at one end. High-voltage cables themselves can also use shielded power cables, with the shielding layer grounded at both ends to confine the magnetic field. By strictly isolating the wiring, the coupling interference between high-voltage and low-voltage circuits can be reduced by more than 40dB, ensuring the stability of the control system.